Generalize Previews Type code

components/previews/core/previews_experiments.cc

Index: components/previews/core/previews_experiments.cc
diff --git a/components/previews/core/previews_experiments.cc b/components/previews/core/previews_experiments.cc
index afd1fff87f1ee8db5d3751c94b842d02c69d94ed..fa1fd2fe1b34e867f6a96c8b45adf8e846c5251e 100644
--- a/components/previews/core/previews_experiments.cc
+++ b/components/previews/core/previews_experiments.cc
@@ -1,19 +1,20 @@
 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/previews/core/previews_experiments.h"
 
 #include <map>
 #include <string>
 
+#include "base/logging.h"
 #include "base/metrics/field_trial.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "components/variations/variations_associated_data.h"
 
 namespace previews {
 
 namespace {
 
 // The group of client-side previews experiments.
@@ -103,22 +104,28 @@ base::TimeDelta BlackListDuration() {
 
 bool IsIncludedInClientSidePreviewsExperimentsFieldTrial() {
   // By convention, an experiment in the client-side previews study enables use
   // of at least one client-side previews optimization if its name begins with
   // "Enabled."
   return base::StartsWith(
       base::FieldTrialList::FindFullName(kClientSidePreviewsFieldTrial),
       kEnabled, base::CompareCase::SENSITIVE);
 }
 
-bool IsOfflinePreviewsEnabled() {
-  return ParamValue(kOfflinePagesSlowNetwork) == kExperimentEnabled;
+bool IsPreviewsTypeEnabled(PreviewsType type) {
+  switch (type) {
+    case PreviewsType::OFFLINE:
+      return ParamValue(kOfflinePagesSlowNetwork) == kExperimentEnabled;
+    default:
+      NOTREACHED();
+      return false;
+  }
 }
 
 bool EnableOfflinePreviewsForTesting() {
   std::map<std::string, std::string> params;
   params[kOfflinePagesSlowNetwork] = kExperimentEnabled;
   return variations::AssociateVariationParams(kClientSidePreviewsFieldTrial,
                                               kEnabled, params) &&
          base::FieldTrialList::CreateFieldTrial(kClientSidePreviewsFieldTrial,
                                                 kEnabled);
 }